October, 2010.Volume 2 “Where is Lina Lamont When We Need Her?” by Ralph Sargent Welcome again to the AMIA Technical Review. I want to thank the many readers who took the time to write to us with comments and suggestions. Without exception the comments have been positive and complimentary. Let me assure you that we’ll do everything we can to insure a continuance of this reaction! Some suggestions have been made regarding proofing, grammar and spelling. These too have been taken to heart and we shall institute methods to improve in this area. However, I guarantee that undue emphasis on these points will not deter our getting the Tech Review to your eyes in a timely fashion. But to paraphrase what Lina Lamont once said with her usual brilliance, “If we bring a little tech into your humdrum lives, it makes us feel as though our hard work ain't been in vain for nothin'.” Moving on… This issue has seven articles split between two general themes: 1) Casting an eye and ear on historic sound tracks; and 2) New facilities and practices, both analog and digital, in film preservation now and for the future. This last category includes a discussion of the Library of Congress’ new Packard Campus technical facilities, an article on Digital Cinema technologies and the archivist, and two articles on color separation systems, one old and the other new. To help you out on these last two items, I’ve included a page from a book I wrote sometime back, “Preserving the Moving Image.” It will give the reader a quick introduction to color separation systems and hopefully help you better understand both color articles. I hope you’ll find all of the articles interesting and thought‐provoking. Once again we invite you to send us your reactions and comments regarding this issue and ideas or whole articles for the future. To paraphrase from my previous letter… Those of you who feel you have appropriate material to contribute, please feel free to advise us via a thematic proposal or précis of your article. If accepted for publication, your articles should 1 The Tech Review . October, 2010 AMIA Tech Review ©2010. Association of Moving Image Archivists. Editor’s Note. ©2010. Ralph Sargent. be received at the AMIA office no later than six weeks prior to next publication date. (Please email Laura Rooney at the AMIA Office for anticipated publication dates.) All articles or suggestions submitted are subject to review, condensation or augmentation and editing. Publication of the AMIA Tech Review will be web‐based in portrait format. The print version will be found as a PDF. Readers are encouraged to print whatever they wish for their own use; however, all material shall remain the copyrighted property of The Association of Moving Image Archivists or respective copyright holders as indicated and may not be reproduced for any other use in any form without the prior express written permission of the Association or indicated copyright holder. We encourage readers of the AMIA Tech Review to become members of ancillary trade associations such as the National Association of Broadcasters, the Audio Engineering Society, the Society of Television Engineers, the Society of Motion Picture and Television Engineers, etc. Cross‐pollination of technical information is important and we strongly support it! Finally, please let us know what you think. It never hurts to speak your mind in a civil and constructive manner. If there is some aspect of this publication you feel could be improved, please let us know. If there is something you liked, let us know. You get the idea…. Best wishes and see you in Philadelphia in November! Ralph Sargent, editor 2 The Tech Review . October, 2010 AMIA Tech Review ©2010. Association of Moving Image Archivists. Editor’s Note. ©2010. Ralph Sargent. October, 2010.Volume 2 Digital Cinema Technologies From the Archive’s Perspective by Arne Nowak Introduction During the last few years digital technologies have gained much ground in production, editing, post‐ production and exhibition of cinematographic work. This fundamental change of technologies also has had a large impact on archives. On the one hand archives have very successfully implemented digital restoration and digital distribution of films on the internet or via DVDs, as well as to digital cinemas. On the other hand archives will have to adapt and change existing procedures or introduce new processes because they will be confronted with digital material for deposit that is not bound to a carrier medium, as is the case with film or video cassettes. Instead the images and sound will come to the archives in the form of digital computer files. Digital cinema has evolved over the last few years, and even though various alternative systems and solutions are used in different parts of the world, most commercial productions in North America and Europe use a system that has its origin in the Digital Cinema Initiatives1 (DCI). DCI was a joint venture of six major American film production companies which together worked out an open specification for a digital cinema system. Many parts of this specification have been adopted by SMPTE and also transformed into standards by the international standardization organization ISO. This article is intended to give a basic introduction to the technologies and processes that are associated with the DCI / SMPTE digital cinema system. In the following sections I give an overview of the basic technologies that are used, describe important technical details of the Digital Cinema Package (the format that is delivered to the cinemas), point out how these packages can be produced and give some thoughts on implications of this system on archives. 1 http://dcimovies.com/ 1 The Tech Review. October, 2010 AMIA Tech Review ©2010. Association of Moving Image Archivists. Digital Cinema Technologies. ©2010. Arne Nowak. Basic technologies and standards The digital cinema system as it is used today in North America and Europe is defined by a set of SMPTE standards which are mostly based on the voluntary specification of the DCI. Currently, SMPTE standard documents exist and are effective for all essential parts of the systems. Ongoing work in standardization is mostly concerned with additional features and extensions such as the recently released additional frame rates document that introduces the possibility of other frame rates than the originally specified 24 and 48 FPS. Many of the SMPTE standards for digital cinema also have been adopted by the ISO in its technical committee TC362. The SMPTE standards take care of different important technical aspects of digital cinema. A complete list can be found at http://www.smpte.org/standards/NumberIndex.pdf. The documents describe the D‐ Cinema Distribution Master (DCDM, SMPTE 428), D‐Cinema Packaging (DCP, SMPTE 429), D‐Cinema operations (including key management for encrypted packages, SMPTE 430) and D‐Cinema quality for projection (SMPTE 431). All of these documents contain references to other standards from SMPTE, ISO and other organizations that describe certain technical details, and there exist also several SMPTE Recommended Practice documents for D‐Cinema. The DCI Digital Cinema System Specification, which is available for download free of charge at http://www.dcimovies.com, contains very detailed descriptions of the technical aspects and serves as a good reference, since huge parts of this specification have been included in the SMPTE standards. The DCI Specification additionally contains very detailed information about all encryption and content security related aspects and serves as the operational guideline for the studios that are involved in the DCI. All technologies that are used within the SMPTE / DCI D‐Cinema system are openly available and can be used free of license or patent fees of any kind by all interested parties. This allows any person, company or organization to develop systems or software that comply with these standards. In fact, besides several commercial solutions to create Digital Cinema Packages (DCP), at least one free open source software implementation exists to do this. The SMPTE / DCI D‐Cinema system is centered on the DCP. This is the compressed format in which digital movies are delivered to the cinema and from which they are projected. D‐Cinema is essentially a file and IT‐oriented environment. The DCP is a set of files that contain images, sound, subtitles and additional files to control playback and optional encryption of the content. Images and sound are stored in separate files that are called track files and there is the possibility to divide a movie into several reels. That means the complete set of images and sound data and also subtitles are split into several files of arbitrary duration. The playback order is controlled by a Composition Playlist (CPL) that includes references to the image, sound and subtitle files. A DCP can contain more than one CPL. This makes it possible, for example, to create a multi‐language DCP that contains only one set of image track files that are used for all language versions but several sets of sound track files, one for each language. Each CPL now contains references to the shared image track files and the sound track files for each language. 2 http://www.iso.org/iso/iso_technical_committee?commid=48090 2 The Tech Review. October, 2010 AMIA Tech Review ©2010. Association of Moving Image Archivists. Digital Cinema Technologies. ©2010. Arne Nowak. The following sections of this article give explanations of the technical details of a DCP, including encryption and access control, the mastering and creation of DCPs, and discuss the relevance of DCPs in film archives and implications related to their use as a deposit, exhibition and distribution format. The Digital Cinema Package Overview The main intention of the DCP is to serve as a flexible and secure format for delivery and projection of digital movies on a very high quality level.